Array(T)
Inherits Comparable < Indexable::Mutable < Indexable < Enumerable < Iterable < Reference < Object
An Array is an ordered, integer-indexed collection of objects of type T.
Array indexing starts at 0. A negative index is assumed to be relative to the end of the array: -1 indicates the last element, -2 is the next to last element, and so on.
An Array can be created using the usual new method (several are provided), or with an array literal:
Array(Int32).new # => []
[1, 2, 3] # Array(Int32)
[1, "hello", 'x'] # Array(Int32 | String | Char)See Array literals in the language reference.
An Array can have mixed types, meaning T will be a union of types, but these are determined
when the array is created, either by specifying T or by using an array literal. In the latter
case, T will be set to the union of the array literal elements' types.
When creating an empty array you must always specify T:
[] of Int32 # same as Array(Int32)
[] # syntax errorAn Array is implemented using an internal buffer of some capacity
and is reallocated when elements are pushed to it when more capacity
is needed. This is normally known as a dynamic array.
You can use a special array literal syntax with other types too, as long as they define an argless
new method and a << method. Set is one such type:
set = Set{1, 2, 3} # => Set{1, 2, 3}
set.class # => Set(Int32)The above is the same as this:
set = Set(typeof(1, 2, 3)).new
set << 1
set << 2
set << 3Instance methods
fetch(index) без значения по умолчанию — IndexError как в Ruby (диапазон в сообщении — от -size до size, как в Ruby: -3...3).
flatten(depth): ограничение глубины. Тип результата — Array(Object): рекурсивные союзы типов не выражаются в Crystal (см. DIFFERENCES.md).
Ruby set-операции: intersection/union/difference с несколькими аргументами.
Returns an array of the maximum count elements, sorted descending.
It compares using <=> so it will work for any type that supports that method.
[7, 5, 2, 4, 9].max(3) # => [9, 7, 5]
%w[Eve Alice Bob Mallory Carol].max(2) # => ["Mallory", "Eve"]Returns all elements sorted descending if count is greater than the number of elements in the source.
Raises Enumerable::ArgumentError if count is negative or if any elements
are not comparable.
Returns an array of the minimum count elements, sorted ascending.
It compares using <=> so it will work for any type that supports that method.
[7, 5, 2, 4, 9].min(3) # => [2, 4, 5]
%w[Eve Alice Bob Mallory Carol].min(2) # => ["Alice", "Bob"]Returns all elements sorted ascending if count is greater than the number of elements in the source.
Raises Enumerable::ArgumentError if count is negative or if any elements
are not comparable.
sample(n) в порядке Ruby (rb_ary_sample): j = RAND_UPTO(len-i) из сжимающегося множества — фактический индекс = j + число выбранных ≤ j.
sample в порядке Ruby (rb_ary_sample): один элемент — limited(len-1).
Fisher-Yates в порядке Ruby (rb_ary_shuffle) поверх MT19937.
Ruby Array#slice(range): ["a","b","c"].slice(1..2) → ["b","c"].
Passes elements to the block until the block returns a falsey value,
then stops iterating and returns an Array of all prior elements.
[1, 2, 3, 4, 5, 0].take_while { |i| i < 3 } # => [1, 2]